A diode, such as a PIN diode, may be particularly useful as a radio frequency (RF) switch. One example PIN switch configuration is a series-shunt configuration. A series-shunt configuration of PIN diode switches is typically used to achieve a relatively high isolation, which may be particularly important in high frequency applications, for example at or above 1 GHz.
To achieve the relatively high isolation in a high power application, for example >10 W, a relatively high reverse bias voltage is used. The series diode and shunt diode of a particular switched path must be forward and reversed biased complementarily to minimize insertion loss and maximize isolation. DC blocking capacitors are often placed between the series and shunt diode to allow RF to pass freely and facilitate the independent DC biasing with low-voltage forward bias supplies. DC blocking capacitors, for example, allow for relatively low DC power consumption, but are less efficient in terms of using more discrete components, consuming printed circuit board (PCB), and diminishing isolation at higher frequencies.
Alternatively, to forward bias the shunt diodes, the shunt diode forward bias current may come from a relatively high voltage supply. While using a relatively high voltage supply decreases PCB space with respect to the DC blocking capacitors and has relatively good isolation at higher frequencies, static DC power consumption is high.
Packaged series-shunt PIN diode switches may provide increased thermal performance and higher isolation. However, packaged series-shunt PIN diode switches are generally not available with DC blocking capacitors isolating the series and shunt diodes.